LOW-ENERGY NEUTRAL-ATOM IMAGING TECHNIQUES FOR REMOTE OBSERVATIONS OF THE MAGNETOSPHERE

Recent developments in the detection of neutral atoms mill enable construction of space-based imagers that may reveal the global structure and dynamics of the terrestrial magnetosphere. The principal technical challenge of imaging low-energy neutral atoms having energies <30 keV is separating them from the intense uv background, to which their detectors are sensitive, with minimal loss of trajectory and energy information. Three instrument concepts for separating low-energy neutral atoms from the background uv are discussed: neutral-atom ionization via transmission through an ultrathin carbon foil and subsequent electrostatic deflection, uv grating polarizers and attenuators, and high-frequency shutters. Hardware associated with each of these concepts is mated to a detector section that provides trajectory, coincidence, and, if required, time-of-flight measurements.